Previous methods of marking glass have ranged from stickers and non-permanent decals which are temporary and have otherwise, no theft deterrent or permanent identification properties, to engraving the glass surface with a carbide or diamond tipped bit in which requires a skilled craftsman's freehand to obtain an aesthetically pleasing result and which also has a drawback of the possibility of the glass cracking by an unskilled hand, to various methods of chemical etching to obtain a permanent etch mark and also using a focused laser light to mark glass items.
Over the past one hundred years many inventions have been developed proposing different incarnations of glass etching chemical compositions, it is known from these that the silicon dioxide which constitutes a large part of the makeup of glass can be etched by a reaction with sulfuric or fluoric acid, or one or a composition using a combination of hydrogen fluoride, sodium fluoride, potassium fluoride, ammonium fluoride, potassium biflouride, sodium biflouride, ammonium biflouride, ammonium borofluoride and ammonium silicofluoride.
Various processes have been suggested using the above mentioned articles and the subsequent herein mentioned patents. U.S. Pat. No. 95,617 suggests utilizing lead letters first placed upon to a horizontal glass surface. A coating non-reactive to a chemical glass etching compound is applied to the glass in the spaces around which the lead is laid. The letters are then taken from the glass to expose the uncoated glass underneath in which the suggested etchant, hydrogen fluoride, is to be applied and wherein the exposed glass is allowed to react with the etchant, thereby permanently marking the glass in just the non-coated areas of the glass where the etching compound was applied. Methods utilizing a non-reactive coating to mask the glass, either by employing lead letters as suggested in the above mentioned patent or by hand with a non-reactive oily pen as described in U.S. Pat. No. 7,276,181 example 7, to create a “chemical” or “oil” mask wherein a glass etchant can then be applied to the non-coated glass are extremely tedious as each step requires a skilled craftsman and hand application can be time and labor intensive to effectively mask the negative image of the desired mark.
U.S. Pat. Nos. 4,585,514 and 4,781,792 suggests methods for marking glass employing a masking tissue film and a known reactive glass etching compound and a procedure for attaching the mask tissue film to the glass employing a liquid solution which has no mechanical adhesive properties but merely held in place with a liquid Van der Waals (capillary) action. Using these protocols will not only result in a mask which may move upon the plane of the glass while wet when the etching compound is brushed on to the mask, thereby skewing the permanent mark, it also may result in which their mentioned liquid mask securing solutions, which are noted not to let fully evaporate, from diluting the etching compound and/or allowing the etching compound to leach into the aqueous securing solution thereby allowing the etching compound to get into and under the still wet tissue mask. Specific to U.S. Pat. No. 4,781,792, the mentioned alkaline aqueous solution is used to concurrently secure the mask to the glass and to neutralize the etchant compound after sufficient time for marking has elapsed when the mask is detached from the glass. Because this aqueous solution is basic and consequentially has a PH value of over 7, and it is mentioned to not let the basic neutralizing solution to evaporate from the stencil mask before applying the glass etching solution acid having a PH value lower than 7, the alkaline liquid solution will combine with the marking compound and render the etchant somewhat PH neutralized and diluted, thereby resulting in an incomplete mark. Moreover, a stencil template which is produced by their recommended practice of using an impact printer such as a typewriter does not result in clear and sharp lines or details also resulting in a low dots per inch, because the print head impacting the stencil media does not fully remove and only displaces the desired resist areas in which constitutes the design to be marked, thereby leaving some resist material remaining in the area desired to be etched.
U.S. Pat. No. 5,151,572 discloses a method of making a stencil employing a laser cutting device to “cut” a desired design, with the aid of a computer and layout software, into an adhesive backed label with a releasable backing strip. The laser is applied to the stencil label with backing strip to vaporize the polyester topcoat, and the adhesive bottom coat thereby leaving an appropriate stencil mask in which is to be applied to a glass part and chemically etched. While this method tries to eliminate some of the flaws inherent with U.S. Pat. Nos. 4,585,514 and 4,781,792, it brings about some misgivings of its own. A laser light with accompanying user interface design and computer hardware is very big and cumbersome, requires corded power and input/outputs and is costly to acquire the equipment, maintain the equipment and to cut each stencil mask.